Forte delle Saline is a fortified structure built by the Sienese in the fifteenth century (the project of 1469) as amended and expanded by the Spanish in 1630. The fort was used to control the adjacent salt marshes, an important resource of the territory, but also the river port of Albegna and the passage on the pillow Giannella.
Currently it is publicly owned and is used as an archive of the Superintendent.